Production of a color image by using a silver halide photographic light sensitive material is carried out through the reaction process in which the main developing agent is oxidized at the same time when the silver halide grains in the light sensitive material are reduced and then the obtained oxidant reacts with a coupler which has been contained in the light sensitive material so as to form a dye. Three kinds of couplers such as yellow, magenta and cyan are usually used so as to reproduce colors by the subtractive color process.
Each coupler is added to a silver halide photographic emulsion by dissolving it in a substantially water-insoluble high-boiling point organic solvent and, if necessary, adding another auxiliary solvent.
Fundamental properties demanded to each coupler are to be highly soluble to the high-boiling point organic solvents and auxiliary solvents, to have a good dispersivity and a good stability in silver halide emulsion so as not to be deposited in it, to have an excellent spectral characteristic which results a good color tone and a distinct color image in a wide range of color-reproducible area and the toughness of the obtained color image to light, heat and humidity.
2-anilino-5-pyrazolones are widely used as the couplers to produce magenta dye. These couplers are inferior in solubility to high-boiling point organic solvent and in light proof and are not satisfactory in color tone. The searching for various kinds of chemical groups to obtain dispersion proofness has been carried out. Among them, acyl amide dispersion-proof group containing a terminal phenoxy group which is described in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 40804/1976 and 126831/1976 is excellent in solubility and color tone.
However, it is not sufficient in light proof and, moreover, the dispersion solution which uses this coupler is inferior in retention stability.
Various kinds of organic oxidation inhibitors have been developed so as to improve light proof of magenta and other dyes. Examples are the compounds described in Japanese Patent O.P.I. Publication Nos. 72225/1977, 20327/1978, 48538/1979 and 152225/1977. These oxidation inhibitors do, however, not display a sufficient effect to the above-mentioned couplers but represent only incomplete stability and sometimes occur perspiration (a phenomenon to produce oil drop on the surface of the photosensitive material by diffusion and condensation of oil contained in the photosensitive material when it is kept in a high temperature and humidity conditions). Light-proof property of the material can be improved in accordance with the increase of the amount of added oxidation inhibitor but the stability of dispersion solution decreases and the perspiration increases.
The use of surface active agents seems to be effective for the improvement of the stability of dispersion solution. Examples are surface active agents described in Japanese Patent O.P.I. Publication Nos. 46733/1974 and 173470/1987 and Japanese Patent Examined Publication No. 21372/1985. Their effects are, however, not sufficient. Almost of all other surface active agents are good in coating property and antistatic property but are not good in the stabilization of dispersion solution. These weak points can be improved to some extent by the increase of the amount of the added surface active agent; but, at the same time, it causes the increase of perspiration.
Anyhow, it has been impossible to improve all of these properties - color tone, light proof and perspiration and retention stability of the dispersion solution. A method to solve all of these problems at the same time has long been expected.